This invention relates to rotary driven members and more particularly to a sprocket or gear capable of absorbing torsional shocks and vibrations in a power drive train.
Sprocket and gear assemblies which smooth and dampen torsional shock loading and minimize noise and vibration by the use of resilient cushioning means, such as rubber cushions or springs, adapted to yieldingly transmit rotary motion between mating lugs of an integral hub and rim assembly are known. For instance, see U.S. Pat. Nos. 486,068 (Allington), 2,873,590 (Croset), 2,961,856 (Selzer), 3,257,860 (Runde et al.), and Danish Pat. No. 13952 (U.S. Class 74-243.R). See also Koppers Company "Holset Resilient Couplings" catalog, March 1973, for disclosure of other typical applications, including elastic shaft couplings. These cushioned assemblies may be used with chain, timing belt (positive drive belting), or direct gear drives, as elastic shaft couplings, or for like applications where torsional elasticity is needed. However, despite the provision of cushioning means in the assemblies, these prior art devices suffered from at least one of two problems. First, the bearing load was not symmetric with respect to the sprocket, causing the rim to either wobble axially or orbit radially with respect to the hub, and in some cases causing the hub and rim to lose concentricity under dynamic loading. Another problem derived from the nature and configuration of the resilient cushioning means, which permitted only minimal angular deflections (e.g., up to 7.degree. ) between the rim and hub portions, insufficient for drives or other applications experiencing high peak torsional shock loads.